The overall objective of the six month project is to develop a sustained release fluoride dentifrice formulation based on microcapsules with a duration of 12-24 hours. In Phase I sodium fluoride microcapsules will be prepared and characterized for NaF content, geometry, and fluoride release profile. A glycerin based formulation will be developed for suspending the microcapsules and the stability of the fluoride microcapsules in the formulation determined. These studies will form the basis for more extensive preclinical testing of the formulation in vitro and in animals which is planned for Phase II. The goal of Phase III is to secure an IND and proceed with clinical trials of the dentifrice in collaboration with a commercial organization. The principal investigator was involved in two previous studies of microencapsulated sodium fluoride sponsored by NIDR. Sodium fluoride microcapsules, 38-300 micron, were recently prepared at BIOTEK using a fluidized bed process. Preliminary studies show fluoride release to be related to capsule geometry, thus confirming the predictions of release theory. Studies of fluoride release in glycerin/water mixtures show that glycerin would be an excellent candidate for suspending and storing NaF microcapsules without leaching fluoride from the capsules. The final consumer product will be a multicomponent toothpaste similar to Aquafresh in which the glycerin microcapsule suspension is stored in parallel with a water based paste. The two will be mixed immediately before use when the tube is squeezed to deliver the two pastes to the toothbrush.